Ghost Gavel

A board with a gavel is shown. Although the gavel will drop under its own weight, the magicain is able to make the gavel tap at will. When handed out, the gavel does not move.

Ideas include:

*Lie Detector. *Answer Questions. *Do simple mathematics. *Clever mechanical prop. *Made in wood. *Easy to do. The gavel is completely under performers control at all times and has no Magnets, Batteries, Electronics.